Fire retarding treatment

ABSTRACT

A process is illustrated for rendering a water repellent fabric fire retardant without adversely affecting the fabric&#39;&#39;s water repellent characteristics. The water repellent fabric is treated with an aqueous medium containing a fire retarding agent and a thermally degradable surfactant such as the diacetyl dilauryl amide derivative of triethylenetetramine and then dried. On drying, the surfactant degrades and the water repellent characteristics of the fabric are restored.

United States Patent Goldbeck et al.

[451 Apr. 11, 1972 [54] FIRE RETARDING TREATMENT [72] Inventors: Leroy J. Goldbeck, Neenah; Norbert L.

Van Den Elzen, Hilbert, both of Wis.

[73] Assignee: Kimberly-Clark Corporation, Neenah,

Wis.

[22] Filed: Sept. 18, 1970 [21] Appl. No.: 73,412

[52] US. Cl ..1l7/46 CA, 117/62, 117/76 T, 117/102 R, 117/135.5, 117/136, ll7/137, 117/138 [51] Int. Cl. ..B44d l/46, C09k 3/28 [58] Field ofSearch ..1 17/62,76 T, 102 R, 135.5, 117/136,137,138, 46 CA [56] References Cited UNITED STATES PATENTS 3,103,254 9/1963 Stedman ..117/137 X 2,421,218 5/1947 Pollak 2,640,000 5/1953 Seyb et a1. ..1 17/76 3,062,678 11/1962 McCluer ..1 17/62 X 2,422,730 6/1947 Hoffman ..117/136 2,911,322 11/1959 Klein et a1 ..117/76 3,265,527 8/1966 Adelman 1 ..117/62 3,154,426 10/1964 Kohnken.... 17/46 X 2,443,617 6/1948 Homan ..1 17/46 X Primary Examiner-William D. Martin Assistant Examiner1-larry J. Gwinnell AttorneyWolfe, Hubbard, Leydig, Voit & Osann [57] ABSTRACT A process is illustrated for rendering a water repellent fabric fire retardant without adversely affecting the fabrics water repellent characteristics. The water repellent fabric is treated with an aqueous medium containing a tire retarding agent and a thermally degradable surfactant such as the diacetyl dilauryl amide derivative of triethylenetetramine and then dried. On drying, the surfactant degrades and the water repellent characteristics of the fabric are restored.

4 Claims, 1 Drawing Figure PATENTEDAPR H I972 INVEN TORS LEROY J: GOLDBECK Nozssnr L. wu mflzew FIRE RETARDING TREATMENT DESCRIPTION OF THE INVENTION The present invention relates to the preparation of fire retardant materials and, more particularly, to fire retardant treatments for materials which have previously been treated for water repellency.

Many methods are presently available for rendering fabrics fire retardant. Ordinarily, such is accomplished by simply saturating the fabric with an aqueous medium containing a dissolved or dispersed fire retarding agent in an amount sufficient to achieve the desired level of fire retardance. In order to sufficiently wet the fabric with the retarding agent, it is customary practice to include a wetting agent or surfactant in the aqueous treating medium. After saturation, the fabric is simply dried and ready for use.

While achieving fire retardance by a technique such as above described is quite simple when only fire retardance is required, certain problems can arise when the fabric is to possess other characteristics. For example, when a combination of fire retardancy and water repellency is required, simple fire retarding treatment steps are frequently not satisfactory, particularly when the fabric to be treated has been initially rendered water repellent. In such instances, it is difficult to maintain the initial level of water repellence due to the presence of the surfactants in the fire retarding compositions. Accordingly, many available techniques for imparting fire retardancy to a fabric which has previously been treated for water repellency results in either a decrease in the water repellent characteristics of the fabric or failure to achieve adequate fire retardance due to the necessity of using inadequate quantities of surfactants in order to preserve the fabrics repellent characteristics.

Accordingly, it is a principal object of the present invention to provide a method for imparting fire retardancy to a fabric which has been treated for water repellency without adversely affecting the water repellent characteristics of the fabric. A related object is to provide such a method which can be accomplished using conventional aqueous treating techniques.

Other objects and advantages of the present invention will become apparent upon reading the following detailed description of the invention, taken in conjunction with the drawing which illustrates a schematic arrangement of apparatus for carrying out the present invention.

While the invention is susceptible of various modifications and alternative constructions, there is shown in the drawing and will herein be described in detail the preferred embodiments. It is to be understood, however, that it is not intended to limit the invention to the specific forms disclosed. On the contrary, it is intended to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Briefly stated, the method described herein involves treating a water repellent fabric with an aqueous medium containing a fire retarding agent and a particular type of surfactant. The surfactant employed is effective in promoting wetting of a fabric with the retarding agent so as to achieve the desired level of fire retardance, but is capable of losing its wetting capacity when the fabric is heated to an elevated temperature. Thus, by using the method described herein, a water repellent fabric can be rendered fire retardant without an adverse effect on the fabric s water repellency.

Turning now to the drawing, there is schematically illustrated an arrangement of apparatus which can be used in accomplishing the present process. As shown, a web of fabric is initially rendered water repellent at the treatment station 12 which is illustrated as being that apparatus to the left of the verticle phantom line A. As illustrated, the fabric 10 is impregnated with an aqueous medium 14 containing a suitable water repellent by passing the fabric around the roll 16 submerged in the tank 18 containing the aqueous medium 14. After emerging from the tank 18, the fabric 10, now impregnated with the water repellent, is passed through the press rolls 20, 22 to remove excess repellent and, thereafter, dried by being passed through the oven 24.

The manner of treating the fabric for water repellency is quite conventional and a variety of known techniques other than that specifically illustrated in the drawing can be used. When an aqueous treating method such as that illustrated is employed, the repellent contained in the tank I8 is ordinarily present in an amountof about 05-10 grins/liter of water with the particularly appropriate amount being based on the repellent employed. Drying of the web after impregnation is ordinarily accomplished at a temperature of about 300-350 F. for about 5-30 seconds. On a dry solids basis, water repellent fabrics usually contain the water repellent in an amount of about 0.1-2 percent, based on the weight of the fabric.

The water repellent applied to the fabrics illustrated herein is not particularly important. Accordingly, any of the known water repellents can be employed, through fiuoro chemicals such as those manufactured by the 3M Company and designated as FC-805, FC-808, and FC-8l7 have been found to be particularly effective. However, examples of other useful repellents include wax dispersions such as Cravenette N-l 5, and Impregnole" SP and FH and pyridinium repellents such as Cravenette 610. Other examples of useful water repellents are given in the American Dyestuff Reporter, 58 (20): 15-19, 45 (Oct. 6, 1969). As indicated previously, the repellent is usually applied to the fabric as a water solution or dispersion and, after application, the fabric is dried. While, with respect to many water repellents, drying under the conditions recited above is adequate to develop their repellency characteristics, it is also frequently desirable to further cure a repellent. Curing at about 350 F. for 10-30 seconds is usually sufficient to fully develop repellency properties, through, with respect to some, curing for up to about 5 minutes or more is needed. Curing can also result in economy in water repellent use.

Referring again to the drawing, when fire retardancy is not required, the water repellent fabric can be simply passed to the storage station 26 for future use. On the other hand, where fire retardancy is desired, the water repellent fabric is conveyed to the fire retarding treatment station 28 (the illustrated apparatus above the horizontal phantom line B), and it is with respect to this portion of the illustrated apparatus that the .present inventiomis particularly concerned. As shown, the

fabric 10 made water repellent at the station 12, is rendered fire retardant by passing the fabric 10 around the roll 30 submerged in the tank 32 which contains an aqueous medium 34 containing a water repellent and a water soluble surfactant. Excess repellent is removed from the saturated fabric by passage of the fabric through the press rolls 36, 38. Thereafter, the fabric is dried and the surfactant degraded by passing the fabric through the oven 40. Subsequently, the fire retardant, water repellent fabric can be rolled up and stored for future use.

As has been indicated, it is an important aspect of the present invention that the surfactant used in applying the fire retardant be water soluble and thermally degradable at a temperature which does not adversely affect the fabric. In this latter respect, the surfactant should degrade at a temperature of about 250-400 F. with exposure times of about 0.3-3 minutes, the longer times being associated with the lower temperatures.

Surfactants with the above characteristics which are particularly useful in the present invention are the diacetyl dihigheralkyl amide derivatives of triethylenetetramine. Such surfactants have the following basic structural formula:

I CH2 CHaC wherein X is 6-12 inclusive. A preferred surfactant of the above type which is thermally degradable at about 250 -300 F. is the diacetyl dilauryl amide derivative of triethylenetetramine (the above structure wherein X is 9). This surfactant is commercially available from Sun Chemical Co. and is sold under the tradename Mykon NRW-Il."

A variety of well known fire retardants can be used in accomplishing the method of the present invention. Useful retardants, both of the inorganic salt and organic type, are given in the journal Textile World 119 (I) 102-106 (1969) Oct. Particularly useful fire retardants are those containing nitrogen, phosphorus, boran, sulfur, and/or halogen substituents. Specific examples of useful compounds include water soluble salts such as ammonium chloride, ammonium sulfamate, sodium borate, and mono and (ii-ammonium phosphate, as well as other retardants such as barium meta borate, zinc borate complexes, urea, boric acid, antimony chloride, antimony oxychloride, antimony trioxide, titanium acetate, and titanium oxychloride.

In preparing the aqueous fire retarding medium useful herein, it is simply necessary to mix the fire retarding agent and the surfactant together in the presence of water. Ordinatily, the concentration of fire retardant is about 4-20 wt. percent based on the total weight of the aqueous medium with the surfactant being present in an amount of about 2-8 wt. percent, based on the weight of the fire retardant. The retardant pick up by the fabric must be sufficient to impart the desired degree of fire retardance and, to this end, a retardant pick up of about 4-6percent, based on the weight of the dry fabric, is ordinarily useful. In addition to the surfactant and fire retarding agent, other ingredients can also be present in the aqueous medium. For example, anti-yellowing agents are frequently also included.

As is apparent from the above discussion, the present invention is applicable to a wide variety of fabrics wherein it is desired to impart fire retardancy while maintaining water repellency. The invention is especially applicable to that class of fabrics generally categorized as nonwovens and, in particular, those nonwovens which are principally comprised of tissue, such as cellulose wadding, containing a suitable reinforcing means such as a scrim or a web of drafted or carded fibers.

The following description further illustrates the method of the present invention. Apparatus similar to that depicted in the drawing was employed. The water repellent fabric treated at the station 28 comprised a nylon scrim having two plies of creped cellulose wadding (each having a weight of about 8 lbs/2,880 ft?) adhesively bonded to each side of the scrim. Water repellence was achieved by impregnating the fabric with 3Ms FC-805. The aqueous fire retarding medium 34 in the tank 32 was comprised of the following ingredients:

863 parts by weight 12 parts by weight l20 parts by weight 5 parts by weight After saturation with the aqueous fire retarding medium, the fabric was heated at about 300 F. for about 30 seconds to dry the fabric and degrade the surfactant. Based on the dry fabric, the retardant add on was about 12 wt. percent.

The fabric prepared as described above possessed the combination of good fire retardancy and good water repellency. Thus, as has been shown, the method described herein fully satisfies the aims and objectives of the present invention.

We claim as our invention:

1. In the process for rendering a water repellent fabric fire retardant comprising treating the water repellent fabric with an aqueous medium containing a fire retarding agent and a water soluble surfactant and thereafter heating the fabric, the improvement wherein the water soluble surfactant is thermally degradable and fabric heating is accomplished for a time and at a temperature sufificient to degrade the surfactant and not adversely affect the fabric.

2. The process of claim 1 wherein the surfactant is a diacetyl dihigheralkyl amide derivative of triethylenetetramine.

3. The process of claim 1 wherein the surfactant is a diacetyl dilauryl amide derivative of triethylenetetramine.

4. The process of claim 3 wherein fabric heating is accomplished at about 250-400 F. for about 0.3-3 minutes. 

2. The process of claim 1 wherein the surfactant is a diacetyl dihigheralkyl amide derivative of triethylenetetramine.
 3. The process of claim 1 wherein the surfactant is a diacetyl dilauryl amide derivative of triethylenetetramine.
 4. The process of claim 3 wherein fabric heating is accomplished at about 250*-400* F. for about 0.3-3 minutes. 